UNIVERSITY  OF   CALIFORNIA  PUBLICATIONS 

COLLEGE  OF  AGRICULTURE 

AGRICULTURAL  EXPERIMENT  STATION 

BERKELEY,  CALIFORNIA 


THE  OLIVE  INSECTS  OF 
CALIFORNIA 


BY 
E.  O.  ESSIG 


BULLETIN  No.  283 

September,   1917 


UNIVERSITY  OF  CALIFORNIA  PRESS 

BERKELEY 

1917 


Benjamin  Ide  WheelerJ  President  of  the  University. 

EXPERIMENT  STATION  STAFF 
HEADS  of  divisions 

Thomas  Forsyth  Hunt,  Director. 

Edward  J.  Wickson,  Horticulture   (Emeritus). 

Herbert  J.  Webber,  Director  Citrus  Experiment  Station;   Plant  Breeding. 

Hubert  E.  Van  Norman,  Vice-Director;  Dairy  Management. 

William  A.   Setchell,  Botany. 

Myer  E.  Jaffa,  Nutrition. 
*Robert  H.  Loughridge,  Soil  Chemistry  and  Physics  (Emeritus). 

Charles  W.  Woodworth,  Entomology. 

Ralph  E.  Smith,  Plant  Pathology. 

J.  Eliot  Coit,  Citriculture. 

John  W.  Gilmore,  Agronomy. 

Charles  F.  Shaw,  Soil  Technology. 

John  W.  Gregg,  Landscape  Gardening  and  Floriculture. 

Frederic  T.  Bioletti,  Viticulture  and  Enology. 

Warren  T.  Clarke,  Agricultural  Extension. 

John  S.  Burd,  Agricultural  Chemistry. 

Charles  B.  Lipman,  Soil  Chemistry  and  Bacteriology. 

Clarence  M.  Haring,  Veterinary  Science  and  Bacteriology. 

Ernest  B.  Babcock,  Genetics. 

Gordon  H.  True,  Animal  Husbandry. 

James  T.  Barrett,  Plant  Pathology. 

Fritz  W.  Woll,  Animal  Nutrition. 

Walter  Mulford,  Forestry. 

W.  P.  Kelley,  Agricultural  Chemistry. 

H.  J.  Quayle,  Entomology. 

Elwood  Mead,  Rural  Institutions. 

J.  B.  Davidson,  Agricultural  Engineering. 

H.  S.  Reed,  Plant  Physiology. 

D.  T.  Mason,  Forestry. 

W.  L.  Howard,  Pomology, 
t  Frank  Adams,  Irrigation  Investigations. 

C.  L.  Roadhouse,  Dairy  Industry. 

William  G.  Hummel,  Agricultural  Education. 

John  E.  Dougherty,  Poultry  Husbandry. 

S.  S.  Rogers,  Olericulture. 

David  N.  Morgan,  Assistant  to  the  Director. 

Mrs.  D.  L.  Bunnell,  Librarian. 

Division  of  Entomology 
C.  W.  Woodworth  G.  P.  Gray 

W.  B.  Herms  G.  A.  Coleman 

E.  C.  Van  Dyke  S.  B.  Freeborn 

J.  C.  Bradley  H.  H.  Severin 

E.  O.  Essig  E.  R.  deOng 


*  Died  July  1,  1917. 

f  In  co-operation  with  office  of  Public  Roads  and  Rural  Engineering,   U.    S. 
Department  of  Agriculture. 


THE  OLIVE  INSECTS  OF  CALIFORNIA 

By  E.  0.  ESSIG 


INTRODUCTION 

As  compared  with  other  trees  in  California,  the  olive  is  attacked 
by  comparatively  few  insects  and  in  many  localities  is  almost  entirely 
exempt  from  regularly  destructive  pests.  The  industry,  however,  is 
so  large  and  conditions  of  insect  work  so  varied  that  it  seems  advisable 
to  collect  all  of  the  available  information  regarding  the  insects  which 
infest  this  crop  in  one  paper.  The  subject  matter  is  discussed  under 
the  two  general  heads :  I,  the  more  important  olive  insects  in  Califor- 
nia, and  II,  insects  of  minor  importance  to  olive  trees  in  California. 
There  is  also  included  at  the  end  a  brief  discussion  of  some  of  the 
most  important  olive  insects  of  other  states  and  foreign  countries 
which  have  not  gained  access  to  this  state  or,  as  in  a  few  cases,  do 
not  attack  the  olive  here. 

The  writer  is  specially  indebted  to  Prof.  C.  W.  Woodworth  of  the 
Division  of  Entomology  and  to  Prof.  Frederic  T.  Bioletti  of  the 
Division  of  Viticulture  and  Enology  for  many  helpful  suggestions  and 
corrections. 

I.   THE    MORE    IMPORTANT    OLIVE    INSECTS    IN    CALIFORNIA 

THE  BLACK  SCALE 

Saissetia  oleae  (Bernard) 
Figures  1  and  2 

The  black  scale  is  the  commonest  and  most  troublesome  insect  pest 
of  the  olive  in  California,  but  there  are  many  districts  which  have 
always  been  practically  free  from  serious  attacks.  The  young  are 
liable  to  be  killed  by  hot,  dry  weather  and  therefore  the  insect  does 
not  find  the  climatic  conditions  of  the  warmer  valleys  so  favorable 
to  its  growth  as  those  along  the  coast.  However,  it  is  gradually 
encroaching  upon  territory  claimed  a  few  years  ago  to  be  absolutely 
immune  because  of  the  hot,  dry  summers. 

In  most  other  states  and  especially  in  Europe,  this  insect  is  com- 
monly known  as  the  olive  scale  or  olive  cochineal  and  has  received 
the  specific  name  oleae  from  the  olive  which  it  commonly  attacks. 
In  California,  it  has  always  been  called  the  black  scale,  either  because 
of  the  dull  black  color  of  most  of  the  females  or  because  this  insect  is 
the  one  chiefly  responsible  for  the  growth  of  the  black  smut  fungus 
over  the  leaves,  stems  and  fruit  of  the  infested  plants.      It  has  one 


44 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


of  the  most  characteristic  markings  to  be  found  among  the  scale  in- 
sects, consisting  of  a  very  plain  elevated  letter  "H"  upon  the  backs 
of  both  the  young  and  old  females.  The  male  scales,  which  are  much 
smaller  than  the  females,  are  usually  entirely  wanting  and  when  pres- 
ent appears  as  very  thin,  transparently  white  exuviae,  from  which  the 
males,  after  undergoing  transformation,  emerge  as  tiny  two-winged 
insects.      This  occurs  when  the  females  are  about  one-third  or  half 


Fig.  l 


Fig.  2 


Fig.  1. — The  black  scale,  Saissetia  oleae    (Bern.).     The  young  females  as  they 

appear  on  the  olive  leaves  and  twigs  during  the  winter  months.     (Original). 
Fig.  2. — Adult  females  of  the  black  scale,  Saissetia  oleae  (Bern.),  on  an  olive  twig. 

(Original.) 

(Photos  by  Div.  Sci.  Illust.,  Univ.  Calif.) 


grown.  After  mating,  the  males  die,  and  so  it  is  that  even  when 
present,  because  of  their  small  size,  entirely  different  form,  and  short 
life,  they  are  not  generally  known  to  the  orchardists.  The  females, 
however,  are  always  in  evidence,  and  do  the  damage  to  the  trees. 
They  reach  maturity  in  most  localities  during  the  months  of  June, 
July  and  August  and  lay  from  100  to  3000  small  oblong  or  oval 
whitish  or  amble-colored  eggs  which  remain  beneath  the  large,  nearly 
hemispherical  hollow  body,  the  underside  of  which  shrivels  as  the 


THE  OLIVE  INSECTS  OF  CALIFORNIA  45 

eggs  are  laid  till  scarcely  more  than  a  thin  shell  remains.  Upon 
hatching,  the  young,  which  have  much  endurance  for  such  small 
creatures,  crawl  from  beneath  the  bodies  of  the  parents  and  seek  suit- 
able feeding  places.  The  majority  first  settle  on  the  undersides  of 
the  leaves  along  the  midribs  while  the  remainder  seek  the  smaller 
twigs.  Many,  of  course,  perish  during  the  winter,  but  by  spring  there 
are  still  great  numbers  remaining,  and  chiefly  those  which  settled  on 
the  twigs.  Those  on  the  leaves  also  move  to  the  twigs  and  remain 
there  during  the  rest  of  their  existence  or  until  the  old  dead  bodies 
fall  off.  The  cold  winter  months  are  not  conducive  to  growth,  but 
with  the  coming  of  the  warm  spring  days,  development  is  rapid  and 
the  excrement,  known  as  honeydew,  begins  to  appear  in  quantities  over 
the  trees.  This  sweet  excrement  is  the  food  of  a  black  smut  fungus, 
which,  though  an  after-effect,  is  the  most  serious  feature  about  this 
and  many  other  scale  insects.  It  is  the  prevention  of  the  smut  fungus 
that  most  often  prompts  the  control  of  the  black  scale.  The  fungus 
serves  as  a  good  index  to  the  time  for  spraying. 

The  black  scale  is  a  general  feeder  and  attacks  a  large  and  ever- 
increasing  number  of  plants,  the  known  list  for  all  countries  including : 
almond,  Antidesma,  apple,  apricot,  mountain  ash,  aster,  beech,  buck- 
thorn, camellia,  California  nutmeg,  deodar  cedar,  Cestrum,  chrysan- 
themum, citron,  Duranta,  eucalyptus,  fig,  fuchsia,  geranium,  grape, 
grapefruit,  Orevillea,  Grewia,  groundsel  tree,  guava,  English  holly, 
mountain  holly  or  Christmas  berry,  St.  John's  wort,  jasmine,  Irish 
juniper,  laurel,  lemon,  black  locust,  honey  locust,  magnolia,  mahogany, 
maple,  Maytenus,  Melaleuca,  Myoporum,  nightshade,  oleander,  olive, 
orange,  trifoliate  orange,  orchids,  palms,  periwinkle,  pigeon  pea,  pear, 
pepper  tree,  phlox,  plum,  pomegranate,  poplar,  privet,  prune,  rose 
rubber,  sage,  sumach,  sycamore,  tangerine,  sago  palm,  strawberry 
tree,  Thespesia,  Veronica,  and  watermelon. 

Considering  the  whole  state,  very  little  has  been  done  towards  the 
control  of  the  black  scale  on  olive  trees.  In  a  few  of  the  large  com- 
mercial plantings,  particularly  along  the  coast  regions,  some  attention 
is  given  to  the  insect  and  control  measures  are  employed  whenever 
necessary.  These  control  measures  have  been  well  worked  out  and 
have  given  very  satisfactory  results.  In  a  few  instances  fumigation 
has  been  used  in  the  citrus  districts  with  marked  success,  but  the  cost 
as  compared  with  spraying  is  so  much  greater  that  the  latter  practice 
is  now  almost  universally  followed  where  treatments  are  advantageous. 
The  hardiness  and  resistance  of  the  olive  trees  are  remarkably  great, 
making  it  possible  to  apply  very  strong  sprays  without  injury  to 
the  fruit  or  foliage.      Normally,  the  dormant  sprays  for  deciduous 


46  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

fruit  trees  are  used,  but  it  is  advisable  in  most  cases  to  reduce  their 
strength  about  one-fourth  to  one-third,  especially  if  the  fruit  is  well 
matured  on  the  trees.  The  materials  used  are  chiefly  oil  emulsions, 
miscible  oils  and  soap  powders,  although  the  rosin  wash  and  the 
distillate-caustic  soda-water  mixture  have  also  been  used  with  success. 
The  oil  emulsions  may  be  prepared  at  home  or  purchased  from  reliable 
manufacturers.  Many  growers,  realizing  the  difficulty  of  securing 
proper  materials  for  home  preparations  and  the  variability  of  the 
homemade  mixtures,  even  under  the  best  conditions,  prefer  to  buy 
manufactured  products,  especially  when  only  small  quantities  are 
needed.  For  those  who  desire  a  homemade  product  the  following 
formula  may  be  followed  for  a  crude  oil  emulsion  ■} 

Crude  oil  (21°  to  24°  Baume)  15  gallons 

Liquid  soap  (or  20  lbs.  hard  fish  oil  soap)  3 

Water    175 

Place  the  required  amount  of  water  in  the  spray  tank  and  add  the  liquid  soap ; 
agitate  thoroughly  and  pour  in  the  crude  oil,  continuing  the  agitation  until  the 
mixing  is  complete  and  no  free  oil  remains  on  the  surface  and  also  during  the 
application  to  the  trees. 

The  distillate-caustic  soda-water  mixture  is  easily  prepared  as 
follows : 

Distillate    (28°    Baume)  7    gallons 

Caustic  soda  (95%)  5  to  7  pounds 

Water to  make  200  gallons 

First  dissolve  the  caustic  soda  in  a  small  amount  of  water  and  add  to  the 
water  in  the  spray  tank;  begin  the  agitation  and  slowly  add  the  distillate,  con- 
tinuing the  agitation  during  the  application.  This  spray  will  also  remove  the 
lichens  or  moss  from  the  trees. 

The  rosin  wash  is  chiefly  used  for  young  and  tender  nursery  stock, 
because  it  does  not  cause  the  injury  often  following  the  application 
of  the  previously  named  materials  in  such  cases.     The  preparation  is : 

Rosin  10  pounds 

Caustic  soda  (76%  to  95%)  3  to  2% 

Fish  oil  iy2 

Water to  make  50  gallons 

To  a  gallon  of  hot  water  in  an  iron  kettle  add  the  fish  oil  and  the  rosin  and 
heat  until  the  latter  is  softened;  after  first  dissolving  the  caustic  soda  in  a  small 
quantity  of  water  add  it  and  stir  the  mixture  thoroughly,  after  which  pour  in 
enough  water  to  make  fifty  gallons  of  spray  material. 

i  All  of  the  spray  formulae  are  reduced  to  meet  the  average  needs  for  olive 
trees.      They  may  be  strengthened  by  one-fourth  to  meet  extraordinary  conditions. 


THE  OLIVE  INSECTS  OF   CALIFORNIA 


47 


The  miscible  oils  cannot  be  satisfactorily  prepared  at  home  and 
should  be  purchased  from  a  reliable  manufacturer  or  dealer  and  used 
according  to  the  directions  that  accompany  them. 

The  oil  emulsions,  distillate-caustic  soda-water  mixture  and  the 
miscible  oils  often  separate  in  the  spray  tank  if  the  water  contains 
much  mineral  matter  and  should  be  applied  only  with  a  good  power 


Fig.  3. — The  ivy  or  oleander  scale,  Aspidiotus  liederae  (Vail.),  and  its  work  on  the 
fruit  of  the  olive.     (Original.) 

(Photo  by  Div.   Sci.   Illust.,   Univ.   Calif.) 


machine  with  a  forceful  agitator,  which  must  be  kept  going  during 
the  entire  process  of  application  to  avoid  oil  injury  to  the  trees. 

The  soap  powders  are  a  revival  in  a  somewhat  different  form  of  an 
old  spraying  material  (soap)  and  in  the  present  form  are  compara- 
tively new  in  spraying  work  and  are  meeting  with  much  favor  because 
of  their  comparatively  cheapness,  ease  of  handling  and  efficiency. 
They  are  put  up  in  barrels,  and  are  ready  to  add  directly  to  the 
water  in  the  spray  tank,  dissolving  readily  in  cold  water  with  a  small 
amount  of  stirring  or  agitation.  The  average  dose  is  about  one  pound 
to  every  five  gallons  of  water. 


48  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

The  best  time  to  kill  the  scale  is  during  the  period  just  following 
hatching,  usually  in  August  and  September,  but  fair  results  may  be 
expected  at  any  time  from  the  middle  of  August  to  the  first  of 
January. 

The  proper  quantity  of  material  should  be  applied  in  the  form 
of  a  rather  coarse  driving  spray  under  a  pressure  of  from  100  to  200 
pounds.  For  the  average-sized  tree  from  five  to  seven  gallons  should 
be  sufficient  to  thoroughly  cover  every  portion  adequately. 

A  sufficient  number  of  scales  to  produce  any  noticeable  amount  of 
honeydew  and  cause  a  corresponding  degree  of  smutting  should  be 
sufficient  evidence  to  warrant  spraying. 

In  spraying  an  orchard,  it  is  important  to  keep  the  following  in 
mind: 

1.  In  case  of  doubt  as  to  the  strength  of  materials  to  use,  spray  a 
few  trees  to  ascertain  results  before  treating  the  entire  orchard. 
Allow  about  two  weeks  to  get  the  full  results  of  the  chemicals. 

2.  Never  spray  when  the  orchard  is  in  need  of  water,  as  severe 
burning  of  fruit  and  foliage  may  result.  Irrigate  first  or  wait  until 
after  the  first  rain. 

3.  Do  not  spray  during  excessively  hot  weather  or  when  hot  winds 
are  blowing. 

4.  Do  not  spray  within  several  weeks  before  picking,  if  possible,  as 
spotting  of  the  fruit  may  result. 

The  control  of  the  black  scale  by  natural  enemies  has  long  been 
the  subject  of  much  experimental  work  without  any  very  definite  re- 
sults. True,  a  number  of  predaceous  and  parasitic  insects  have  been 
introduced  to  combat  it,  but  their  combined  efforts  are  not  sufficient 
to  be  a  reliable  factor  in  the  control  of  the  pest  in  the  orchards. 

The  predaceous  insects  include  the  following:2  the  black  ladybird 
beetle,  Rhizobius  ventralis  Er.,  the  ashy-gray  ladybird  beetle,  Olla 
abdominalis  (Say),  Lindorus  lopantkae  (Blaisd.),  the  steel-blue  lady- 
bird beetle,  Orcus  chalybeus  (Boisd.)  and  Axion  plagiatus  Oliv.  Of 
these,  the  first  is  the  only  one  of  importance.  It  was  first  introduced 
into  the  olive  orchards  of  Santa  Barbara  County  and  has  since  been 
distributed  generally  throughout  the  state.  The  larvae  and  adults 
feed  upon  the  black  scale  and  in  some  districts  become  quite  abundant. 
Lindorus  lopantkae  (Blaisd.)  is  also  quite  widely  distributed  and 
preys  partially  upon  the  black  scale.  The  others  seem  never  to  be- 
come very  numerous  or  important. 


2  For  a  complete  list,  discussion  and  illustrations  of  predaceous  and  para- 
sitic insects  of  the  black  scale,  see  Bui.  223,  Calif.  Agr.  Exp.  Station,  July,  1911, 
bv  Prof.  TT   J   Ch-,o^a  '  & 


by  Prof.  H.  J.  Quayle. 


THE  OLIVE  INSECTS  OF   CALIFORNIA  49 

Among  the  parasitic  insects,  are  the  scutellista,  Scutellista  cyanea 
Mots.,  also  known  as  the  African  fly,  Dilophogaster  californicus 
(How.),  Aphycus  sp.  and  the  lecanium  parasite,  Coccophagus  lecanii 
(Fitch).  Of  these  the  scutellista  is  by  far  the  most  important  and 
at  times  becomes  remarkably  numerous,  infesting  nearly  every  egg- 
laying  female  of  the  scale.     The  larvae  feed  upon  the  eggs,  but  usually 


Fig.  4. — The  ivy  or  oleander  scale,  Aspidiotus  hederae    (Vail.).     Adult  females 
and  young  on  an  olive.     (Original.) 


leave  enough  to  insure  little  or  no  diminution  in  the  number  of  scales 
for  the  next  year.  Though  not  at  all  dependable,  it  is  often  relied 
upon  by  growers  to  do  what  can  be  accomplished  with  certainty  with 
sprays,  with  the  result  that  considerable  loss  is  caused  by  the  omission 
of  control  measures  every  year.  The  other  parasites  listed  work 
much  more  spasmodically  and  little  real  investigation  has  ever  been 
done  to  ascertain  whether  they  do  any  good  or  not. 


50  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

The  state  insectary  is  still  continuing  its  endeavors  to  introduce 
parasites  which  will  prey  more  effectively  upon  the  immature  stages 
of  the  black  scale  and  it  is  hoped  that  every  success  will  attend  their 
efforts  so  as  to  reduce  the  expensive  operation  of  spraying. 


THE  IVY  OE  OLEANDER  SCALE 

Aspidiotus  hederae   (Vallot) 

Figures  3-6 

In  some  parts  of  the  San  Joaquin  and  Sacramento  valleys,  this 

insect  often  becomes  quite  abundant  on  the  leaves,  and,  in  a  few 

instances,  on  the  fruit  of  the  olive  trees.      In  the  latter  case,  it  is 


Fig.  5. — The  ivy  or  oleander  scale,  Aspidiotus  hederae   (Vail.),  on  an  olive  leaf. 

(Original.) 

(Photo  by  Div.   Sci.   Illust.,   Univ.   Calif.) 

specially  annoying  to  the  growers  of  ripe  pickling  olives.  The  in- 
fested fruits  become  spotted  because  the  retarded  development  of  the 
tissues  around  the  scales  leaves  pits  or  depressions  and  the  checking 
of  the  coloring  in  these  places  causes  them  to  remain  green  while  the 
rest  of  the  fruit  assumes  the  natural  dark  color  (fig.  3).  The  insect 
gets  its  common  names  from  the  two  plants  most  universally  attacked, 
although  in  this  state  others  are  as  commonly  infested.  It  is  what 
is  called  a  true  armored  scale;  that  is,  the  female  has  over  its  small, 
nearly  circular,  yellow  body  a  protection  in  the  form  of  a  thin  gray 
or  whitish  circular  scale  about  one-twelfth  of  an  inch  in  diameter. 
The  scale  of  the  male  is  more  elongated  and  somewhat  smaller,  the 
mature  insect  being  small  and  winged  as  in  the  case  of  the  black 
scale.      In  most  cases,  the  scales  are  scattered  over  the  surface  of 


THE  OLIVE  INSECTS  OF   CALIFORNIA 


51 


the  foliage  in  a  very  irregular  way,  while  in  others  they  are  so  thick 
as  to  overlap.  On  the  fruit  of  the  olive  they  occur  in  small  colonies, 
each  group  often  being  composed  of  a  single  female  and  her  progeny. 
The  young  are  born  alive  and  move  freely  until  the  first  molt,  when 
they  lose  their  legs  and  must  remain  throughout  the  rest  of  their  exist- 
ence in  one  spot.  Breeding  continues  almost  throughout  the  entire 
year  in  many  parts  of  the  state,  but  it  is  much  more  rapid  throughout 
the  summer  months. 

As  in  the  case  of  the  black  scale,  the  list  of  known  food  plants  is 
very  large  and  ever  increasing,  including,  in  all  countries,  the  follow- 


Fig.  6. — The  ivy  or  oleander  scale,  Aspidiotus  Jiederae   (Vail.).     Drawing  of  the 
pygidium  of  a  female.      Greatly  enlarged.      (Original.) 


ing:  Acacia,  aloe  or  century  plants,  asparagus  ferns,  betel  nut,  box- 
wood, buckthorn,  butcher's  broom,  California  laurel  or  pepperwood, 
cactus,  camellia,  carob,  Carpodetus  serratus,  cherry,  citron,  clover, 
currant,  daphne,  date  palms,  eucalyptus,  fan  palms,  genista,  grape- 
fruit, grasses,  Hakea  alliptica,  holly,  English  ivy,  kentia  palms,  lemon, 
Macrozamia,  madder,  magnolia,  manzanita,  maple,  mistletoe,  Monte- 
rey pine,  mulberry,  Myrsine  retusa,  nightshade,  oleander,  olive, 
orange,  orchids,  oxalis,  pepper  tree,  periwinkle,  plum,  pomegranate, 
Prunus  ooldus,  holly  oak,  red-bud,  redwood,  rubber,  sago  palm, 
sumach,  umbrella  plant,  umbrella  tree,  Vitex  litt oralis,  Vriesia 
splendens,  yew  and  yucca.      From  this  list  it  will  be  seen  that  in- 


52  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

festation  may  occur  from  a  large  number  of  sources  outside  the 
orchards. 

The  control  of  this  insect  is  seldom  attempted,  for  the  actual  loss 
does  not,  in  most  cases,  justify  the  cost  of  treatment.  "Where  control 
is  desirable  the  oil  emulsion  and  miscible  oil  sprays  as  recommended 
for  the  black  scale  should  be  used. 

Natural  enemies  have  never  been  considered  of  any  consequence 
in  the  control  of  this  scale,  although  there  are  both  ladybird  beetles 
and  hymenopterous  parasites  that  prey  upon  it  in  California  as  else- 
where. 

THE  BRANCH  AND  TWIG  BORER 

Polycaon  confertus  Leconte 

Figure  7 

The  work  of  this  beetle,  which  consists  of  small,  round  holes  from 
one-eighth  to  one-fourth  of  an  inch  in  diameter  and  usually  less  than 
an  inch  in  length  at  the  base  of  a  bud  or  in  the  fork  of  a  small  branch, 
is  familiar  to  many  orchardists.  Occasionally  one  also  finds  the 
beetle  itself  at  work  in  the  holes.  It  is  small,  brown  and  black  and 
about  half  an  inch  long.  The  object  of  its  work  is  probably  to 
secure  food,  as  no  eggs  are  deposited  or  young  reared  in  anything  but 
dead  wood,  while  the  burrows  in  orchard  trees  are  always  made  in 
perfectly  healthy  and  living  tissue.  The  injury  is  due  to  the  breaking 
of  the  twigs  at  the  holes,  and  the  improper  pruning  of  the  trees  which 
results.  The  young  trees  suffer  most,  though  old  trees  are  quite  as 
commonly  attacked.  Plants  known  to  be  thus  injured  are:  almond, 
apple,  apricot,  cherry,  currant,  fig,  grape,  lemon,  olive,  orange,  peach, 
pear,  plum  and  prune.  As  previously  stated  the  insect  normally 
breeds  in  dead  wood,  chiefly  of  the  madrone,  oak,  and  old  grape  canes 
where  the  larvae  may  often  be  found  in  great  numbers. 

The  beetle  occurs  generally  throughou  the  state,  but  has  been  most 
annoying  in  the  Sacramento,  San  Joaquin,  and  Santa  Clara  Valleys 
and  the  central  coast  region.  The  attacks  are  spasmodic  and  of  short 
duration  and  the  damage  done  through  a  succession  of  years  is  really 
slight.  Regular  control  measures  have  never  been  tested  out  because 
they  are  generally  unnecessary.  The  elimination  of  the  dead  wood 
in  which  the  insect  breeds  might  be  suggested  as  a  preventive  meas- 
ure and  in  young  orchards,  where  the  attacks  are  severe,  it  might  be 
advisable  to  go  over  the  trees  about  once  a  week  and  kill  the  beetles 
in  the  burrows  with  a  wire  or  knife  blade. 


THE  OLIVE  INSECTS  OF   CALIFORNIA 


53 


THE  OLIVE  BARK-BEETLE 

Luperisinus  calif ornicus  Swaine 

Figures  8  and  9 

Though  at  present  a  comparatively  unknown  insect,  this  beetle 

may  possibly  become  one  that  must  be  reckoned  with  in  the  future, 

if  we  are  to  judge  by  what  little  is  now  known  regarding  its  work. 

A  few  adults  were  first  taken  by  H.  A.  Weinland,  then  Horticultural 

Commissioner  of  San  Diego  County,  in  the  Mission  Valley  near  the 


Fig.  7. — The  branch  and  twig  borer,  Polycaon  confertus  Lee.     Larva  and  adult. 

Enlarged.     (Original.) 


city  of  San  Diego  on  May  17,  1915,  and  forwarded  to  the  writer  with 
the  information  that  they  were  found  injuring  a  living  olive  tree  and 
might  prove  to  be  a  serious  pest.  Other  specimens  followed  from 
the  same  source  on  May  27  along  with  a  piece  of  limb  showing  the 
work  of  the  beetle  and  containing,  within  the  burrows,  a  few  cocoons 
of  a  hymenopterous  parasite.  On  January  27,  1916,  the  present 
Horticultural  Commissioner,  Mr.  H.  M.  Armitage,  sent  in  a  large 
number  of  the  beetles  as  well  as  specimens  of  their  work  and  a  number 
of  the  parasites  mounted  on  slides.  The  insect  proved  to  be  new  to 
the  university  staff  and  they  were  forwarded  to  Mr.  J.  M.  Swaine, 
Department  of  Agriculture,  Dominion  of  Canada,  a  specialist  in  this 


54 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


family  of  beetles,  who  pronounced  it  a  new  species  and  gave  it  the 
scientific  name,  Luperisinns  calif  or  niciis?  For  a  common  name  the 
writer  has  proposed  the  olive  bark-beetle,  which  seems  to  be  sufficiently 
descriptive. 


Fie.  8, 


— The  olive  bark-beetle,  Luperisinus  calif ornicus  Swaine.      Work  and 
^  holes  made  by  the  larvae  and  adults  on  an  olive  limb.     (Original.) 

(Photo  by  Div.   Sci.   Illust.,   Univ.   Calif.) 


exit 


The  insect  is  a  small,  robust  beetle  about  one-eighth  of  an  inch 
long,  black  with  whitish  scales  forming  a  more  or  less  definite  pattern 
on  the  back,  as  shown  in  the  drawing  (fig.  9).  The  legs  and  most 
of  the  antennae  are  reddish  and  the  entire  body  is  covered  with  small 
simple  and  plumose  hairs  of  various  sizes.     In  general  shape  and  size, 


s  Canadian  Entomologist,  vol.  XT/VTII,  no.  6,  pp.  190-192,  June,  1916. 


THE  OLIVE  INSECTS  OF  CALIFORNIA 


55 


the  adults  resemble  very  closely  the  fruit-tree  bark-beetle,  Eccopto- 
g aster  rugulosus  (Ratz.),  a  common  pest  to  deciduous  fruit  trees  in 
various  parts  of  the  state.  The  work  also  resembles  that  of  this 
beetle  and  consists  in  the  destruction  of  the  cambium  layer  by  numer- 
ous small  burrows  (fig.  8)  which  may  entirely  girdle  the  infested 
portions    of    the    trees.      The    perfectly    round    entrance    and    exit 


A  D  E 

Fig.  9. — The  olive  bark-beetle,  Luperisinus  calif ornicus  Swaine.    A,  adult ;  B  and 
C,  leg  and  tarsi;  J),  plumose  hairs  from  body;  E,  antenna.    Enlarged.    (Original.) 

holes  of  the  adults  through  the  bark  are  the  only  distinct  external 
evidences  of  the  work,  excepting  the  general  unhealthy  appearance 
of  the  infested  trees.  The  insects  apparently  prefer  sickly  or  dying 
trees  and  breed  abundantly  in  them  as  well  as  in  the  dead  prunings. 
However,  like  many  of  the  orchard  bark-beetles,  they  will  not  hesitate 
to  attack  perfectly  vigorous  and  sound  trees  in  close  proximity 
to  their  breeding  places,  especially  if  an  entrance  may  be  gained 
through  a  sunburned  or  wounded  spot. 

The  distribution  of  the  species  is  not  well  known.  Besides  the 
infestation  in  San  Diego  County,  already  referred  to,  adults  were 
taken  at  Camp  Greely,  Fresno  County,  as  early  as  1909  by  Mr.  Ralph 
Hopping,4  but  no  host  plants  were  recorded,  the  specimens  having 

4  Canadian  Entomologist,  vol.  XLVIII,  no.  6,  p.  192,  June,  1916. 


56  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

been  collected  in  sweepings  in  the  chaparral  belt  at  an  elevation  of 
3000  feet.  So  far  there  have  been  no  reports  of  its  attacking  olive 
trees  in  Fresno  County.  On  July  9,  1916,  the  writer  received  a  small 
piece  of  olive  bark  from  a  grower  at  Bakersfield,  Kern  County,  show- 
ing small  exit  holes  exactly  like  those  made  by  the  insect  in  question, 
with  the  statement  that  the  insect  causing  the  injury  had  badly  at- 
tacked the  young  olive  trees  with  the  result  that  one  was  already 
dying.  The  possibilities  of  its  being  the  same  thing  are  very  strong, 
though  no  opportunity  has  been  afforded  to  make  a  personal  investi- 
gation. 

As  in  the  case  of  other  orchard  bark-beetles,  the  first  essential  in 
avoiding  attacks  is  to  maintain  a  healthy  condition  of  all  the  trees 
and  to  prevent  sunburn  and  injuries  which  lessen  their  vitality  and 
furnish  the  proper  conditions  for.  the  entrance  of  the  beetles.  The 
immediate  burning  of  all  primings  is  also  important,  to  eliminate 
possible  breeding  places  around  the  orchards.  After  an  orchard  has 
become  infested,  the  only  effective  step  is  to  cut  out  and  burn  all 
infested  limbs  or  trees  as  soon  as  discovered,  to  avoid  spreading  and 
continued  attacks. 

The  small  hymenopterous  parasite5  which  attacks  the  immature 
stages  within  the  burrows  is  not  likely  to  be  of  much  consequence  in 
controlling  the  beetle. 


II.    INSECTS  OF  MINOR   IMPORTANCE  TO  OLIVE  TREES   IN   CALIFORNIA 

Of  the  following  insects,  it  is  not  likely  that  any  will  prove  of 
real  economic  importance,  but  they  are  included  because  they  are 
sometimes  found  infesting  the  olive  trees  and  excite  the  suspicion  of 
the  orchardists. 

1.  The  citrus  thrips,  Scirtothrips  citri  (Moulton).  Taken  in  the 
flowers  of  olive  trees  in  the  San  Joaquin  Valley.6 

2.  The  bean  thrips,  Heliothrips  fasciatus  Pergande.  Reported  as 
seriously  infesting  the  fruit  of  olives  in  San  Joaquin  County  in  1915. 7 

3.  The  net-winged  cicada,  Platypedia  areolata  Uhler.  Sometimes 
punctures  the  small  limbs  of  the  olive  to  insert  its  eggs.  The  punc- 
tures cause  the  twigs  to  become  distorted  or  to  break.  The  distribu- 
tion is  general  throughout  the  state. 


6  The  parasite  has  been  determined  by  Mr.  Eohwer  as  Eophylus,  probably 
sclvwarzi  Eohwer,  through  the  kindness  of  Mr.  Harry  S.  Smith,  superintendent 
of  the  State  Insectary. 

6  Jones,  P.  E.  &  Horton,  J.  E.,  Bull.  no.  99,  pt.  1,  p.  3,  Bur.  Ent.,  U.  S.  Dept. 
Agr.,  1911. 

7  Smith,  H.  S.,  Mthly.  Bull.  Cal.  Hort.  Com.,  vol.  IV,  p.  574,  1915. 


THE  OLIVE  INSECTS  OF   CALIFORNIA 


57 


4.  The  mountain-ash  louse,  Prociphilus  fraxini-dipetalae  (Essig) 
(fig.  10).  This  species  rarely  attacks  the  olive,  having  been  taken  b}^ 
the  writer  on  the  tender  sprouts  at  Berkeley,  1914,  and  on  the  leaves 
at  Corning,  the  same  year,  by  Chas.  B.  Weeks,  Horticultural  Com- 
missioner. 

5.  The  red  scale,  Chrysomphalus 
aumntii  (Mask.).  A  citrus  pest  re- 
ported on  olive  in  the  southern  part 
of  the  state  by  Prof.  H.  J.  Quayle.8 
It  was  recently  received  from  Roy  K. 
Bishop,  Horticultural  Commissioner, 
who  took  it  on  olives  in  Orange 
County.  The  leaves  were  thickly  cov- 
ered. 

6.  The  purple  scale,  Lepidosaphes 
beckii  (Newm.).  Also  a  citrus  pest 
reported  on  olives  in  southern  Cali- 
fornia by  Prof.  H.  J.  Quayle.9 

7.  The  greedy  scale,  Aspidiotus 
camelliae  Sign.  (figs.  11  and  12). 
Very  common  on  the  bark  of  the 
branches,  especially  of  old  suckers.  It 
may  be  easily  mistaken  for  the  ivy  or 
oleander  scale,  the  color  being  much 
the  same,  but  the  outside  shell  is  more 
robust,  nearly  conical  in  shape  and 
with  the  small  exuvia  or  nipple  at  one 
side  rather  than  at  the  middle.  The 
characters  of  the  anal  plate,  as  shown 
under  the  microscope  (fig.  12)  at  once 
separate  it  from  the  ivy  or  oleander 
scale  (fig.  6).  Though  often  abundant,  it  does  not  seem  to  hurt  the 
infested  portions  in  any  noticeable  way. 

8.  The  omnivorous  looper,  Sabulodes  cdberata  Guen.  The  cater- 
pillars of  this  moth  occasionally  feed  upon  the  leaves  of  the  olive 
trees  at  Berkeley. 

9.  The  larvae  of  a  moth  (Pyralid?)  have  been  taken  a  number  of 
times  from  the  knots  on  the  olive  limbs  produced  by  the  bacteria, 
Bacterium  savastanoi  Smith,  by  Prof.  W.  T.  Home  and  Prof. 
Elmore  Chase  at  Fairoaks.      The  soft  spongy  tissues  as  well  as  the 


Fig.     10. — Apterous    females    and 

young  of  the  mountain  ash  louse, 

Prociphilus        fraxini-dipetalae 

(Essig),  on  olive.      (Original.) 


s  Bull.  222,  Cal.  Agr.  Exp.  Sta.,  p.  106,  1911. 
9  Bull.  226,  Cal.  Agr.  Exp.  Sta.,  p.. 325,  1912. 


58 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


harder  portions  of  the  knots  are  thoroughly  perforated  with  the 
burrows  (fig.  13)  made  by  the  caterpillars.  It  does  not  appear  to 
attack  any  other  parts  of  the  trees.  The  caterpillars  are  whitish 
and  about  one  inch  long.  They  are  quite  abundant,  but  so  far  no 
adults  have  been  reared  to  determine  the  species. 


Fig.  11. — The  greedy  scale,  Aspidiotus  camelliae  Sign.,  on  old  olive  suckers. 
The  smut  fungus  which  partially  conceals  the  scales  is  from  black  scale  on  the 
same  tree.     (Original.) 

(Photo  by  Div.   Sci.   Illust.,   Univ.   Calif.) 

SOME  OF  THE  PRINCIPAL  INSECTS  ATTACKING  THE  OLIVE  TREES   IN  OTHER 
STATES    AND    FOREIGN    COUNTRIES 

There  are  but  few  olives  grown  in  other  states  of  this  country, 
consequently  the  list  of  pests  on  them  is  very  short.  In  a  number  of 
foreign  countries,  however,  and  particularly  in  the  Mediterranean 
region,  where  the  olive  has  been  growing  for  ages,  the  number  of 
recorded  pests  is  quite  large.  Among  the  many  there  are  but  few 
serious  enough  to  warrant  control  measures.      In  the  following  list 


THE  OLIVE  INSECTS  OF   CALIFORNIA 


59 


the  most  important  ones  as  well  as  a  number  of  lesser  importance 
which  are  most  often  found  in  published  economic  literature,  are  in- 
cluded so  as  to  give  some  idea  of  the  difficulties  of  growing  olives  in 

other  districts,  as  well  as  to  reflect 
the  benefit  derived  from  excluding 
these  by  state  and  national  quaran- 
tine. 

1.  The     olive     thrips,     Phloeo- 

thrips  oleae  (Costa)  (fig.  14).  This 

insects  attacks  the  leaves  and  fruit, 

Fig.  12.— Drawing  of  the  pygidium  of    producing  the  characteristic  scar- 

the  greedy  scale,  Aspidioius  camelliae    Y{ng  common  to  the  thrips.      It  OC- 

Sign.     Greatly   enlarged.      (Original.)  ,.  .        ,    ~      ,.  ._ 

curs  throughout  Southern  Jiiurope, 

Palestine,  and  South  Africa  and  at  times  is  a  serious  pest. 

2.  The  cicada,  Tibicen  cinctifer  (Uhler).  The  egg  punctures 
weaken  the  small  twigs  and  branches  of  young  olive  trees  in  the  Salt 
River  Valley,  Arizona.10 


Fig.  13. — Work  of  a  caterpillar  on  the  olive  knot  at  Fairoaks.     (Original.) 
(Photo   by   Div.    Sci.   Illust.,    Univ.   Calif.) 


io  Morrill,   Dr.   A.   W;,    7th   Ann.   Kept.    Com.   Agric.    and    Hort.,   p.    34,    1915, 
Cicada. 


60 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


3.  The  olive  psylla,  Euphyllura  olivina  (Costa)  (fig.  15).  This 
insect  infests  the  young  shoots,  buds  and  flowers,  causing  the  latter 
to  drop  and  prevents  the  setting  of  much  of  the  young  fruit.  The 
young  psyllids  are  covered  with  a  white  cottony  material  which 
entirely   hides    them    from    view.       It    occurs    throughout    southern 


Fig.  14. — The  olive  thrips,  Phloeothrips  oleae   (Costa).     Adult  female  and  work 
of  the  insect  on  leaf  and  fruit  of  the  olive.     (Redrawn  from  Del  Guercio.) 


Fig.  15. — The  olive  psylla,  Euphyllura  olivina  (Costa),  a,  colony  of  young  on 
twig  and  flowers;  b,  nymph;  c,  adult.  (Redrawn  from  Coutance  and  Del 
Guercio.) 


Europe  and  in  Palestine  and  is  a  pest  of  minor  importance  except  in 
rare  instances. 

4.  The  scale,  Pollinia  pollini  (Costa).  A  soft  scale  attacking  the 
smaller  branches  of  the  olive  trees  in  southern  Europe.  It  was  once 
taken  on  a  few  olive  trees  at  Pasadena,  California,  which  were  im- 
ported from  Italy  in  1893.      Alexander  Craw  at  once  promptly  de- 


THE  OLIVE  INSECTS  OF  CALIFORNIA 


61 


stroyed  the  infested  trees  and  apparently  exterminated  the  insect.11 
Where  found  it  is  a  pest  of  little  importance. 

5.  The  scale,  Filippia  oleae  (Costa).  A  soft  scale  infesting  the 
olive  leaves  in  southern  Europe,  but  not  nearly  so  serious  as  the  black 
scale,  Saissetia  oleae  (Bern.)  in  the  same  localities,  because  it  produces 
little  honeydew  and  causes  practically  no  smutting. 


V 


a  b  c 

Fig.  16. — The  olive  white  fly,  Aleyrodes  olivinus  Silvestri.     a,  adult;    b,  nymph; 
c,  row  of  eggs.     (Eedrawn  from  Silvestri.) 


Fig.  17 


Fig  .18 


Fig.  17. — Adult  of  the  bark-beetle,  Hylesinus  oleiperda   (Fab.).     (Redrawn  from 

Barbey.) 

Fig.  18. — The  olive  leaf -miner,  Perrisia  oleae  Angelini.     Larva  and  the  mines  on 

an  olive  leaf.     (Eedrawn  from  Del  Guercio.) 

6.  The  terrapin  scale,  Lecamum  nigrofasciatum  Pergrande,  was 
reported  by  Pergrande  as  occurring  on  olive  in  Florida.12 

7.  Leucaspis  riccae  (Targ.).  A  scale  insect  commonly  attacking 
olive  trees  in  southern  Europe  and  northern  Africa,  but  of  little 
consequence  as  a  pest. 

8.  The  rufous  scale,  Selenaspidis  articulatus  (Morgan).  A  scale 
occurring  in  southern  Africa,  West  Indies  and  at  Key  West,  Florida. 

ii  4th  Bien.  Eept.  Cal.  Bd.  Hort.,  p.  438,  1894,  and  5th  Bien.  Eept.  Cal.  Bd. 
Hort.,  p.  43,  1916. 

12  Bull.  18,  N.S.,  U.  S.  Dept.  Agr.,  Bur.  Ent.,  p.  26,  1898. 


62 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


It  attacks  citrus  and  olive  trees  and  is  of  some  importance  as  pest 
to  the  former. 

9.  The  masked  scale,  Chrysomphalus  per  sonatas  (Comst.).  Re- 
ported by  Dr.  T.  D.  A.  Cockerell  as  severely  attacking  olive  trees  at 
Kingston,  Jamaica.13 

10.  The  black  araucaria  scale,  Chrysomphalus  rossi  (Mask.). 
There  are  many  reports  to  the  effect  that  this  scale  is  a  serious  olive 
pest  of  different  parts  of  Australia.14  It  occurs  in  California  on 
Araucaria  spp.,  but  has  shown  no  tendency  to  attack  the  olive  here. 

11.  The  laurel  scale,  Aonidia  lauri  (Bouche),  is  reported  as  seri- 
ously attacking  olive  trees  in  Chili.15 


Fig.  19. — The  olive  fly,  Dacus  oleae  Rossi,  a,  adult  laying  eggs  in  the  fruit 
of  the  olive;  b,  maggot;  c,  puparium;  d,  olive  showing  egg  puncture,  work  and 
exit  hole  of  the  maggot.     (Redrawn  from  Chapelle,  Ruby  and  Martelli.) 


12.  Glover's  scale,  Lepidosaphes  gloverii  (Pack.).  Also  known  as 
the  long  scale.  Attacks  the  olive  in  southern  France  and  northern 
Africa  (Tunis).  It  occurs  in  San  Diego  County,  where  it  sparingly 
attacks  citrus  trees,  but  has  never  been  recorded  on  olive  in  this  state. 

13.  The  scale,  Parlaioria  calianthina  Berl.  e  Leon.  Infests  the  olive 
in  southern  Europe.  Taken  on  imported  olive  trees  from  Greece  in 
quarantine  at  San  Francisco  by  inspectors  in  1915.16 

14.  The  olive  white  fly,  Aleyrodes  olivinus  Silvestri  (fig.  16).  The 
nymphs  of  this  insect  occur  on  the  leaves  of  olive  trees  in  central  and 
southern  Italy  as  well  as  in  Spain,  Tunis,  and  Smyrna.  It  is  not  a 
pest  of  any  serious  consequence. 

15.  The  bark-beetle,  Hylesinus  oleiperda  (Fab.)    (fig.  17).      This 

is  Insect  Life,  vol.  V,  p.  121,  Nov.,  1892. 

I*  French,  C,  Handb.  Destr.  Ins.  Victoria,  pt.  II,  p.  50,  1893,  and  Despeissis, 
A.,  Handb.  Hort.  and  Vit.,  2nd  ed.,  p.  576,  1903. 

is  Philippi,  Dr.  R.  A.,  Insect  Life,  vol.  I,  p.  154,  Nov.,  1888. 

ie  Maskew,  Frederick,  Mthly.  Bui.  Calif.  Hort,  Com.,  vol.  V,  p.  75,  1916. 


THE  OLIVE  INSECTS  OF   CALIFORNIA 


63 


beetle  causes  considerable  damage  in  southern  Europe  by  burrowing 
into  the  older  portions  and  the  limbs  of  the  olive  trees.  It  is,  how- 
ever, primarily  a  pest  of  unhealthy  or  injured  trees. 

16.  Phloeotribus  scarabaeoides  Bern.  (Syn.  P.  oleae  Fabr.). 
Another  bark-beetle  which  makes  galleries  in  the  branches  and  cuts 
off  the  small  twigs  by  its  burrows.  It  is  a  serious  pest  in  Italy.  This 
and  the  preceding  beetle  are  closely  related  to  the  olive  bark-beetle 
recently  discovered  in  California  and  discussed  in  this  paper. 


Fig.  20. — The  olive  tinea,  Prays  oleellus  (Fab.),  a,  caterpillar;  &,  adult;  c, 
work  of  caterpillars  in  seeds;  d,  exit  hole  of  the  caterpillar  in  a  fruit;  e,  webs 
and  work  of  caterpillars  on  buds  and  blossoms;  /  and  g,  work  of  the  caterpillars 
on  the  leaves  of  the  olive.     (Redrawn  from  Chapelle,  Ruby,  and  Del  Guercio.) 


17.  The  olive  weevil,  Rhynchites  ruber  Fairm.  The  adults  feed 
upon  the  tender  leaves  and  tips  of  the  young  shoots  and  puncture  the 
young  fruit.  The  larvae  live  in  the  seeds.  It  does  serious  damage 
at  times  to  the  olive  crop  in  Italy. 

18.  The  olive  leaf -miner,  Perrisia  oleae  Angelini  (fig.  18).  A 
small  cecidomyiid  fly  the  maggots  of  which  mine  the  leaves  of  the 
olive  trees  in  Italy.     It  is  of  little  economic  importance  as  a  pest. 

19.  The  olive  fly,  Dacus  oleae  Rossi  (fig.  19).  This  is  undoubt- 
edly the  most  serious  pest  of  the  olive  to  be  found  anywhere  and  it 
is  very  fortunate  that  it  has  never  gained  access  to  this  state.  It 
occurs  in  the  olive-growing  sections  of  southern  Europe,  Asiatic  Tur- 
key, Palestine  and  northern  and  southern  Africa.  The  fly  punctures 
the  fruit  in  which  it  deposits  its  eggs  and  within  which  the  larvae 


64 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


or  maggots  live  until  mature.  The  work  of  the  maggots  results  in 
the  premature  dropping  of  the  fruit  and  a  diminution  in  the  yield  of 
oil.  Considerable  money  is  spent  annually  by  the  olive  growers  in 
the  control  of  this  pest. 

20.  The  olive  tinea,  Prays  oleellus  (Fab.)  (fig.  20).  This  small 
moth  is  quite  a  serious  pest  in  southern  Europe  and  of  less  impor- 
tance in  Palestine.  The  caterpillars  feed  upon  the  buds,  blossoms, 
and  in  the  seeds  of  the  fruit  causing  much  loss  in  many  cases.  It  is 
probably  second  in  importance  to  the  olive  fly. 


Fig.  21. — The  leopard  moth,  Zeuzera  pyrina  (Linn.).     Adult  female,  caterpillars 
and  chrysalis.     Natural  size.     (After  Britton.) 

21.  The  leopard  moth,  Zeuzera  pyrina  (Linn.)  (^g.  21).  The 
caterpillars  of  this  moth  bore  large  galleries  into  the  wood  of  perfectly 
sound  and  healthy  trees  and  do  considerable  damage  to  olive  trees  in 
southern  Europe,  especially  in  Italy.  It  is  reported  as  the  most 
serious  olive  pest  in  Palestine.  It  also  occurs  in  northern  and  south- 
ern Africa  and  in  Korea,  Japan,  and  along  the  Atlantic  seaboard  from 
Massachusetts  to  the  southern  part  of  New  Jersey.  The  insect  is  a 
very  destructive  pest  to  a  large  number  of  shade  and  forest  trees,  as 
well  as  to  such  cultivated  fruits  as  apple,  cherry,  currant,  pear,  plum, 
and  walnut.  It  is  an  insect  that  we  might  well  take  extra  precautions 
to  keep  out  of  California  by  quarantine  or  other  measures.17 

17  See  Farmers'  Bull.  708,  U.  S.  Dept.  Agr.,  Feb.,  1916,  Howard  and  Chitten- 
den, and  BuU.  169,  Conn.  Agr.  Exp.  Sta.,  Nov.,  1911,  by  Britton  and  Cromie. 


